1. Field of the Invention
This invention relates to switchgear assemblies equipped with drawout devices, specifically in this case being circuit breakers, and, more particularly, it pertains to a rigid frame structure for use in such switchgear assemblies.
2. Description of the Prior Art
Electrical switchgear apparatus, such as circuit breakers and other circuit interrupters, are preferably enclosed within cells or metal-clad cubicles for the safety of personnel as well as for the switchgear apparatus. This is particularly true for switchgear apparatus of the drawout type which is heavy and therefore requires auxiliary means for drawing the switchgear apparatus into and out of the cubicle. Due to the weights of the switchgear and the auxiliary means, considerable stresses are developed. For that reason framework assemblies must comprise rigid corners formed by elongated members or struts, such as shown in U.S. Pat. Nos. 2,167,525; 2,196,399; 3,353,854; and 4,650,085 which disclose the use of supplementary parts for reinforcing the corners which is costly.
Associated with the foregoing is a need for compactness. This can be achieved by reducing the clearance spaces between the cell and the drawout switchgear circuit breaker. The primary limitation on compactness is the front opening of the cell through which the drawout circuit breaker moves into and out of the cell. Heretofore, the corners of such openings have been reinforced by additional parts or squaring members which are costly and, if in the form of gussets, require a larger front opening to accommodate the movement of the switchgear.